Step-by-step rotary electric switch



Jan. 25 1927.

B. C. GARMAN ET AL STEP BY STEP ROTARY ELECTRIC SWITCH Filed Feb. 12,1926 In UE'H Fund .55! Batman Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE.

IBERTRAM CORIBETT GARMAN, OF WEST HAMPSTEAD, LONDON, AND CHARLES OLIVER,01' CHISLEHURST, ENGLAND, ASSIGNORS T OLIVER PELL CONTROL LIMITED, 0]WOOLWICH, ENGLAND, A BRITISH LIMITED LIABILITY COMPANY.

STEP-BY-STEP ROTARY ELECTRIC SWITCH.

Application filed February 12, 1926, Serial No. 87,886, and in GreatBritain July 17, 1925.

This invention relates to step-by-step rotary electric switches of therapid make and break type embodying a number of fixed contacts spacedapart, usually at equal ano gular intervals, around a central operatingspindle, with series of rotating contacts actuated by said spindle andadapted to be moved into and out of engagement with said fixed contactsto close or open one or more electrical circuits.

An object of the present invention is to provide a rotary switch of thistype capable of givin a wider variation of circuit control wit out unduecomplication or multiplication of parts. For instance in modern electricheating and cooking stoves it is desirable to have more than threetemperature changes, which is the number now usually em loyed, and it isto the provision of a sim- 2o pli ed and ractical form of rotary switchcapable of giving this improved temperature grading, that our presentinvention is primarily directed.

The connections required to give three temperature changes are readilyobtainable in a switch with four points or angular switching positionswhich include a single off position. When it is attempted however toprovide more than three heating positions, the

so switch becomes complicated.

For example, in a known form of switch adapted to 've four separateheating positions two ofl sitions are employed so that the switch 0necessity has six points" as or angular switching positions.

In the improved switch of the present invention more than threeelectrical circuit connections and a single ofl' position are obtainedby the employment of a number of 4. points or angular switchingpositions equal only to the number of circuit connections plus the oneoff position;

More particularly the switch of the resent invention embodies aplurality of xed 8 terminals disposed about a central operating spindle,two series of rotating contacts insulated from each other and spacedapart in the lengthwise direction of said operating spindle to engagewith correspondingly I. spaced fixed contacts on the terminals, apluralit of additional rotating contacts dispose intermediate-orexternal tothe two series of rotating contacts and electricallyconnected to one or other of them, and one or more intermediateorexternal-fixed contacts on the terminals to receive the additionalrotating contacts in certain angular positions of the rotating contacts.B external is meant above or below the or inary series of contacts inthe lengthwise direction of the operating spindle.

The switch of the present invention may advantageously be constructed asa double pole switch. The accompanying drawin illustrate a double polereversible switch in accordance with the present invention adapted togive four separate circuit connections corresponding to separatetemperature grades, and one oil position.

In these drawings Fig. 1 is a central sectional view of the switch, withthe cover removed.

Figs. 2 to 6 are developed diagrams of the switch contacts andconnections corresponding respectively to the off and the fourprogressive working positions.

Referring more particularly to Fig. 1:

The switch comprises the usual insulatin base A, operating spindle B andindicatlng knob C. The arrangements for making the switch reversible i.e. rotatable in either direction, are described the specification ofOlivers co-pending patent application filed U. S. A. Feb. 8, 1926 SerialNumber 86,899. Shortly, this reversing arrangement comprises a number offixed abutments M arranged in pairs corresponding to the number ofswitching positions, one abutment of each pair being set above and theother below the central posit-ion of a pawl N which embraces the spindleB and is raised or lowered by a spiral groove 0 so as to escape one orother of the abutments M, when the spindle B is turned in eitherdirection.

Mounted on the base A are five fixed terminals D D D D and D carryingcontact clips or brushes E of the known kind. Free on the spindle B is arotative contact carrying member F connected to the spindle B throughthe driving spring G in the manner described in Olivers saidspecification Ser. No. 86,899. Fixed to the contact carrying member Fare two series of rotating contact blades arranged at top and bottom anddenoted respectively by H and J. The blades H project from a metallicplate H and the blades J from a plate J the two plates being insulatedfrom each other.

In electrical connection with the plate H is a plate K having a singleprojecting blade K, and in electrical connection with the bottom plate Jis a plate L carrying two projecting blades L, one of which latter is inthe vertical roup of blades ner't adiacent to the blade K in theclockwise direction round the switch, and the other blade L is twogroups further removed in the same direction. The top se'ies of contactsII with contact ll are adaoi'ed to make the terminals 3 and 5 (see liveto one pole of the circui nugh ternnnal d the bottom series J areadapted to make terminals l and live to the other pole of the circuit,throi I terminal e which is the other line terminal,

One of the Fred te' In s D carries a brush in an intermediate p gionsuch that it will receive the blades or ll in certain angular positionsof the switch.

Referring now to l" 2 to G:

Tl're lined terminals are 1n..nhered l to 5 in a counter-clockwisedirection, and in order more clearly to explain the action of the switchit is shown applied to the control of two resistances X and Y. of whichY is greaer than I, torn 'ng heating elements, for instance in anelectric stove or heater.

llow in order to obtain with these two elements four separate degrees ofheat they must be connected Both in series (lowest heat). Smaller onesingly. Larger one singly.

(4) Both in parallel (high-est heat).

The terminals 2 and l. are the external line terminals. the resistance Yis connected across terminals 1 and 3, 2.116 the resistance X across theon position in which 2 a: d not engaged.

the terminals Fig. 8 shows st heat position in which the resis I and Yare conn-ected in series the line terminal 2 being connected by a topblad ll to the terminal 5 which engages the int-2"" ediate blade K, thelatter, as above descr red being in an electrical connection with thewhole top series of blades H. The terminal 1 is connected to the terminaby bottom blades J.

Fig. t shows the second hi position employihg the resistance X 0-.

connected in parallel, terminal 2 being connected to 3 by top blades ll,and 1, and t by bottom blades J and intermediate blade L.

In this manner the present invention provides a reversible rotary switchhaving four working positions and in which the number of points orangular switching positions does not exceed the number of workingposit-ions plus a single otl position.

In an alternative construction according to the present invention, theadditional contact blade l1 nniy be arranged above the blades H, or/andthe blades L below the blades J, instead of the intermediate arrangementof blades K and L above described.

In this case, two correspondingly disposed contact clips or brusheswould be provided on the terminals 5.

It is to be understood that the invention is not limited in itsapplication to reversible switches of any type or to any particular form01" operating mechanism but may equally well be applied tounidirectional ro tary switches with any suitable form of operatingmechanism so long as it is of the rapid make and break type.

ll hat we claim is 1. A rapid make and break rotary electric switchembodying a plurality of fixed terminals disoosed about a centraloperating spindle, two series of rotating contacts insulated from eachother and spaced apart in the lengthwise direction of said spindle toengage with correspondingly spaced fixed contacts on the terminals, aplurality of additional rotating contacts disposed in different angularpositions around the switch in planes other than those of the two seriesof rotating contacts and electrically connected to one or other of saidseries, and one or more additional fired contacts to receive theadditional rotating contacts in a certain an gular position or positionsof the switch.

2. A rapid make and break rotary electric switch in accordance withclaim 1 in which the additional rotating and fixed contacts are alldisposed in one plane which is intermediate the planes ot the two usualseries of contacts.

3. A rapid make and break rotary switch in accordance with claim 1 inwhich the additional rotating and fixed contacts are external to theusual series of contacts.

a. A rapid make and break rotary switch adapted to provide tour workingpositions and a single oili position with five fixed terminals and liveangular switching posi tions only, comprising two series of rotatingcontacts of opposite polarity with suitable liXed terminal contacts toreceive them, an additional rotating contact in electrical con nectionwith one or said series of rotating contacts, two additional rotatingcontacts electrically connected to the other said series, all of saidadditional rotating contacts being in difierent angular positions aroundthe switch and in p anes other than those of the two series of rotatingcontacts and one or more additional fixed contacts carried on one of thefixed terminals and a propriately placed thereon to receive the aditional r0- tating contacts in certain switching positions.

5. A rapid make and break rotary switch comprising a plurality of fixedterminals disposed about a central operating spindle which is rotatablein either direction, two series of rotating contacts insulated from eachother and carried by a rotating contactcarrying member with a springinterposed between the spindle and said contact-carrying member, aplurality of fixed contacts to receive the rotating contacts, aplurality of additional rotating contacts disposed in different angularpositions on the contactcarrying member in planes other than those ofthe two series of rotating contacts and electrically connected to one orother of said series, one or more additional fixed contacts to receivethe additional rotating contacts in a certain angular position orpositions of the contact-carrying member, two series of abutmentsdisposed about the operating spindle, and a pawl normally engagmg with apair of said abutments and thereby holding said contact-carrying memberagainst rotation in either direction, the operation being such thatrotation of the spindle in either direction stresses the spring andproduces a relative movement lengthwise 0f the spindle between the pawland the abutments until disengagement takes place, whereupon thecontact-carrying member is rotated by said spring until the pawl becomesengaged by the next abutment of the series which opposes rotation inthat direction.

BERTRAM CORBETT GARMAN. CHARLES OLIVER.

